INTRODUCTION 



198). When two opposite leaves are united by their bases they 

 are called co?inate (from con, together, and ?iatus, born), as in 

 the Yellow-wort (p. 329). 



The point or apex of a leaf may be rounded, as in the Oak ; 



Leaf of Ground Ivy. 



Leaf of Sheep's Sorrel. 



pointed; bristly ; ?ioiched ; or reversedly heart-shaped, as in the 

 leaflets of Wood-Sorrel. 



The margin of the leaf is either entire, or free from indenta- 

 tions, as in the Lily- of-the- Valley ; fringed with hairs, as in young 

 Beech leaves ; waiy, as in the Oak ; cre?iate, or scalloped, as in 

 the Violet j toothed: or iobed. If the teeth point outward it is 

 termed dentate, the Yio\\y\Q2iihe.\ngspi?i02(sIy de?itate ; if upward, as 

 in the Elm, the leaf is senate or saw-edged. 



When a leaf is lobed or divided, its lobes or leaflets are 

 arranged according to its venation, gener- 

 ally palmately or pinnately. The division 

 may extend to various depths from the 

 margin towards the base or midrib, the leaf 

 being termed si7?iple, if it does not extend 

 all the way, and cojupoiind, if it divides the 

 leaf into distinct leaflets. A palmate leaf 

 of three leaflets is called terfiate, as in 

 Trefoils ; one of five, quinate, as in 

 Cinquefoil (p. 148). In pinnate leaves it 

 is important to notice whether there is a 

 terminal (odd) leaflet or not; how many 

 pairs of leaflets there are ; and if these are 

 again divided up {bi-pinnate). If there is a 

 terminal lobe or leaflet larger than the rest, 

 ^s in the White Mustard, the leaf is called 



lyrate. In describing a compound leaf it is generally only necessary 

 to mention the type on which the leaflets are arranged, whether 

 palmate or pinnate, and to describe one leaflet as if it were a 

 simple leaf. If a leaf be divided up into such fine segments that 



Oblique serrate leaf of the 

 Common Elnl. 



